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018530 - SWITCH
Sustainable Water Management in the City of the Future
Integrated Project Global Change and Ecosystems
Deliverable reference number and title
D3.3.8: Professional training workshop. Educational material on water reuse and benefit of the
CW-EF as an environmental friendly technology. The treatment sites may be open to the public
Due date of deliverable: M59 Actual submission date: M60
Start date of project: 1 February 2006 Duration: 60 months Organisation name of lead contractor for this deliverable Revision [draft]
Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) Dissemination Level
PU Public PU PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services)
1
ABSTRACT
This workshop was about a hybrid system of constructed wetland–electro-flocculation polishing
secondary effluent, based on the experiments in Shafdan municipal wastewater treatment plant, Israel.
The purpose of this workshop was to educate professionals about the hybrid process and its
constituents and to demonstrate how to apply it. The invitees to this workshop were engineers,
scientists and professionals from the Tel Aviv-Yafo water corporation, constructed wetland
companies, electro-treatment and wastewater treatment companies and scientists from HUJI and
TAU.
ACKNOWLEDGEMENT
This investigation was partially supported by the EU–SWITCH project and the Italian Ministry of
Environment through Tel-Aviv University. The presented material is part of MSc graduate works of
Barash and Ozer (HUJI), and PhD works of Harif and Ben-Sasson (HUJI) and Milstein (TAU).
2
List of contents: page
ABSTRACT 1
ACKNOWLEDGEMENT 1
1. EF-CW WORKSHOP, SWITCH PROJECT, WP 3.3 3
2. PROFESSIONAL MATERIAL 4
2.1 INTRODUCTION 4
2.2 COMPONENTS OF WASTEWATER TREATMENT BY
WETLAND–ELECTROFLOCCULATION HYBRID SYSTEM 4 2.2.1 Constructed wetland 4
2.2.2 Electroflocculation (EF) 5
2.3 CONSTRUCTED WETLAND-ELECTROFLOCCULATION HYBRID 6
3. REFERENCES 6
APPENDIX A. WORKSHOP PRESENTATIONS 8
CONSTRUCTED WETLANDS, Prof. Avital Gasith 9
SECONDARY EFFLUENT TREATMENT BY CONSTRUCTED WETLANDS,
Dr. Dana Milshtein 42
CONSTRUCTION AND MAINTENANCE OF CONSTRUCTED WETLAND SYSTEMS,
Eli Cohen 65
ELECTROFLOCCULATION: PHYSICAL-CHEMICAL MECHANISMS AND
APPLICATION, Dr. Tali Harif 97
ELECTROFLOCCULATION AND MEMBRANE TREATMENT, Moshe Ben-Sasson 127
ELECTROFLOCCULATION-CONSTRUCTED WETLAND HYBRID SYSTEM,
Alon Barash 150
EF-CW MANUAL AND APPLICATIONS IN INTEGRATED CITY WATER MANAGEMENT,
Prof. Avner Adin 180
APPENDIX B. SCIENTIFIC PUBLICATIONS 186
3
1. EF-CW WORKSHOP, SWITCH PROJECT, WP 3.3
Meetings Room, 6th floor, City Engineering Building,
5 Philon St.,Tel Aviv, 19.12.2010
Program
08:30 Registration
09:00 Opening – Prof. Avner Adin, Prof. Kala Vairavamoorthy (SWITCH)
09:10 Constructed Wetlands – Prof. Avital Gasith, Tel-Aviv University
09:40 Secondary Effluent Treatment by Constructed Wetlands – Dr. Dana Milshtein, Consultant
10:00 Electroflocculation: Physical-Chemical Mechanisms and Application – Dr. Tali Harif,
Atlantium Technologies
10:20 Electroflocculation and Membrane Treatment – Moshe Ben-Sasson, Water corp.
10:40 Coffee Break
11:10 Construction and Maintenance of Constructed Wetland Systems – Eli Cohen, Ayala Water &
Ecology
11:30 Electroflocculation-Constructed Wetland Hybrid System – Alon Barash, Sirkin-Buchner Water
Consulting
11:50 EF-CW Manual and Applications in Integrated City Water Management – Prof. Avner Adin,
Hebrew University
12:10 General Discussion – Prof. Avner Adin and Prof. Avital Gasith
12:30 End
4
2. PROFESSIONAL MATERIAL
2.1 INTRODUCTION
Discharge of effluent into streams and rivers is a common practice worldwide. In arid lands
competition for the freshwater for human use diminishes stream flow and effluents often make much
of the base flow. In such situations stream health and rehabilitation highly depend on effluent quality.
Strict standards for effluent disposal call for economic and efficient treatment alternatives.
2.2 COMPONENTS OF WASTEWATER TREATMENT BY WETLAND-ELECTROFLOCCULATION HYBRID
SYSTEM
2.2.1 Constructed wetland
Constructed wetland (CW) is an environmental friendly technology for treating wastewater or
polishing effluent that is becoming increasingly popular in many parts of the world (Haberl, 2003). It
is designed and constructed based on natural marshes (Kadlec and Wallace, 2008). CWs are often
classified by the pattern of effluent flow in the system (e.g., Brix, 2003). In free-flow (surface flow -
SF) systems wastewater flows above the ground through emerged, submerged and floating aquatic
vegetation. In subsurface flow systems wastewater moves through a porous medium such as gravel or
aggregates, in which rooted hydrophytes grow (USEPA, 2000). Subsurface systems are further
classified into horizontal flow (HF), in which anaerobic conditions prevail, or vertical flow (VF)
which maintains aerobic conditions. Low flow velocities coupled with the presence of roots and solid
substrate, promote settling and filtration of particulate material. Biofilm of diverse microrganisms that
develops on the surface of the porous medium and the submerged vegetation is responsible for most
of the biotransformation and mineralization of pollutants. (e.g, Vymazal, 2003; Kadlec and Wallace,
2008). CWs usually remove organic matter efficiently
Vertical flow wetlands can oxidize organic and ammonia nitrogen (predominant forms of nitrogen in
municipal effluents) effectively. Oxidized nitrogen forms can be further transformed in downstream
HF or SF wetlands to nitrogenous gas (via denitrification), resulting in total nitrogen removal. Since
organic carbon is required for denitrification surface flow wetlands are favored for nitrate removal
under low organic matter conditions (e.g. polishing effluent). Under such conditions decomposed
plant litter can serve as a source for organic carbon.
Recent investigations indicate that VF CW remove efficiently micropollutants such as estrogens (e.g.,
Milstein et al., 2009), pharmaceuticals and personal care products (e.g., Matamoros et al., 2007) but
5
are less efficient in removing phosphorous (P) compounds (Kadlec and Wallace, 2008). Retention of
P in CWs includes peat/soil accretion (mostly in natural and free flow systems), soil adsorption,
precipitation and plant uptake (Vymazal, 2003). In subsurface systems removal by plants is limited
and requires plant harvesting annually. The adsorption and chemical precipitation of phosphorus is
much more vigorous at the initial operation stage because the process has finite capacity (EPA, 2000).
As a result, CW capacity for phosphorous removal is quite limited. Complement process (e.g.
physiochemical process) should be used before or after CW to remove phosphorous efficiently.
2.2.2 Electroflocculation (EF)
Electroflocculation (electrocoagulation) presents an alternative method to conventional (chemical)
flocculation with several advantages: easy operation, lower quantities of produced sludge, avoidance
of chemical usage and, most importantly, no anions such as chloride or sulfate need to be added to the
solution (Mollah et al., 2001). Unlike conventional flocculation in which the coagulants are added to
the water as salts, in the EF process, the coagulants (iron or aluminum) are added to the solution by
dissolving the anode in an electrochemical cell. These coagulant ions ultimately lead to aggregation
of the original particles in the water, which are removed in a later sedimentation or filtration process.
Electroflocculation has been increasingly used in North America for the treatment of industrial
wastewater from pulp and paper industries, mining and metal processing industries, foodstuff wastes,
oil wastes, dyes, suspended particles, chemical and mechanical polishing waste, organic matter from
landfill leachates, deofluorination of water, synthetic detergent effluents, mine wastes and heavy
metal-containing solution (Mollah et al., 2001).
Other investigations indicate that the EFector may have additional abilities in removing pathogens;
heavy metals, and possibly endocrine disruptors. These capabilities can provide a considerable
improvement over conventional or modified CW systems.
If EF unit (EFector) is hybrid with constructed wetland, it may result to shorter residence time, better
water quality, reduced costs for land, construction and maintenance of the constructed wetlands as
well as water loss.
2.3 CONSTRUCTED WETLAND-ELECTROFLOCCULATION HYBRID
The scientific work concentrated on the coupling of Electroflocculation (EF) with constructed
wetland (CW) for improved contaminants removal, phosphorous in particular, from secondary
effluents. The work consisted of three phases: electro-jar testing, continuous-flow EF-filtration (GF)–
6
CW bench scale experimentation and field, half-industrial piloting. P, turbidity, TSS and TOC were
particularly monitored. Laboratory experiments showed that EF-GF effectively removed phosphate
(96%), while CW effectively removed organic matter (85%). Therefore, it seemed that the coupling
of both unit processes would combine their treating abilities. Field pilot results show that EF–GF
removed up to 97% of total phosphorus, resulting in P concentrations of <0.4 mg/L, which are
extraordinary results by any comparison. In addition to phosphorus removal, from the ecological
point of view ammonia removal is as important as phosphorus. One of the advantages of the CW is
efficient ammonia removal (over 90% in the first vertical cell with very low HRT). This is also
important as the CW-EF hybrid consist of a vertical subsurface flow wetland which is the best for
ammonia as well as low-medium concentrations of BOD and TSS.
The system is capable of meaningfully reducing some of the TOC (53%) and most of the TSS. The
EF–CW hybrid action is explained by combining flocculation and adsorption mechanisms produced
by the EF with filtration, sedimentation, sorption, and biodegradation processes in the CW beds.
3 REFERENCES
Brix, H. Plant use in constructed wetland and their function. In Dias, V. and J. Vymazal (Eds.). The
1st international seminar on the use of aquatic macrophytes for wastewater treatment in
constructed wetland, (2003) Portugal pp. 81-109
EPA, Constructed wetlands treatment of municipal wastewater. (2000) EPA/625/R/99/010.
Haberl, R., History of the use of constructed wetland. In Dias, V. and J. Vymazal (Eds.). The 1st
international seminar on the use of aquatic macrophytes for wastewater treatment in constructed
wetland, Portugal (2003) pp. 12.1-12.1
Kadlec, R.H., Wallace, S.D., Treatment wetland, Second edition. CRC Press. (2008) INC, U.S.A.
Matamoros , V., Arias, C, Brix, H. and Bayon, M. Removal of pharmaceuticals and personal care
products (PPCPs) from urban wastewater in a pilot vertical flow constructed wetland and a sand
filter (2007). Environmental Science and Technology 41 pp: 8171-8177.
Milstein, D., Gasith, A. and Avisar, D. Estrogen removal in wetlands – review. International Water
Association (IWA) Newsletter (2009) 35: 17-23.
Mollah, M. Y. A., Schennach R., Parga J. R., Cocke D. L., Electrocoagulation (EC)-science and
applications, Journal of Hazardous Materials B84 (2001) 29-41.
7
Vymazal, J. Removal mechanisms in constructed wetland. In Dias, V. and J. Vymazal (Eds). The 1st
international seminar on the use of aquatic macrophytes for wastewater treatment in constructed
wetland, (2003).Portugal. pp: 219-263.
Constructed Wetlands – a modified natural system in the service of man
modification
Natural Wetland (NW)
Constructed Wetland (CW)
Prof. Avital Gasith, Faculty of Life Sciences, Tel-Aviv University (SWITCH-ISR-19.12.10)
Gasith Ecology Consulting
Photo: Internet Photo: Gasith
9
CWs are wastewater treatment systems
Why do we need CW when WWTP can do a good job?
Gasith Ecology Consulting
Photo: Gasith
10
The unwanted sewage was recognized as a resource
High quality effluent
Effluent Reservoir irrigation
Gasith Ecology ConsultingPhoto: Internet
12
Construction and maintenance cost of high tech. WWTP are relatively high
Usually aimed for large‐scale operations
Membrane Biological Reactor
There is a need for environmental friendly, low‐tech, cheap WWT system that is useful for small‐scale operations
Photo: Internet
Gasith Ecology Consulting 13
What do we expect to achieve by treating wastewater?
• Remove suspended solids• Breakdown organic matter• Remove dissolved nutrients• Remove chemical pollutants
Improved water
quality
Gasith Ecology Consulting 14
The following processes naturally occur in wetlands
• Suspended solids settle or are filtered out;• Organic matter is mineralized by microorganisms;• Nutrients are taken by plants and are transformed by bacteria;
• Inorganic pollutants are transformed chemically or biologically, taken by plants, or are removed from the water by adsorption to surfaces;
Gasith Ecology Consulting 15
Why wasn’t CW technology adopted long ago?
• It was – about 50 years go!• However, it required large flooded areas – an inherent limitation.
• The wetland processes were intensified and became more efficient with the modification of the flow of wastewater through the systems, requiring much smaller area for operation
Gasith Ecology Consulting 16
What is the structure of CWs and how do they function? (Dr. Avital Gasith)
What can CW do? (Dr. Dana Milstein)
How are CW built? (Mr. Eli Cohen)
Gasith Ecology Consulting 17
The basic CW operation unit
Complex physical-chemical-biological
processes
Treatment cell/pond
wastewater effluent
Gasith Ecology Consulting 18
The basic CW unit
The basin is either filled with water or granular bed (usually with hydrophytes)
The flow pattern through the cell varies respectively
wastewater effluent
Gasith Ecology Consulting 19
CWs are categorized by flow pattern
Free Flow/Surface Flow (FF/SF)
Subsurface Flow (SSF)
Ofra Aqua Plants
Ofra Aqua Plants
Gasith Ecology Consulting
Photo: Internet
Photo: Internet
20
Subsurface flow is divided into 2 flow
types:
Sub-surface horizontal flow
Photo: InternetGasith Ecology Consulting 21
Subsurface flow is divided into 2 flow
types:
Sub-surface horizontal flow
Gasith Ecology Consulting
Sub-surface vertical flow
Photo: Internet22
Vertical subsurface flow is further divided into down or up flows
Vertical Down Flow
Vertical Up Flow
Gasith Ecology Consulting 23
Flexibility in design makes modern CW system more efficient
a. Granular bed and plant roots provide greater surface area for microbial biofilm
b. Flexibility in structure and flow pattern determines residence time and enables regulation of aerobic‐anaerobic conditions
Microbial biofilmbed particle
Gasith Ecology Consulting 25
Different flow patterns
Different aerobic-anaerobic conditions
Different microorganisms development and action
Different capacities to remove pollutants
Gasith Ecology Consulting 26
bed particle
The microbial community of biofilmsis relatively long-lived giving chance for establishment fast as well as slow growing microorganisms
Gasith Ecology Consulting 27
Operation under different oxic conditions
• Aerobic conditions: efficient degradation of OM and oxidation of Ammonia (nitrification);
• Anaerobic conditions: Efficient removal of nitrate by denitrification
oxidative and/or reducing conditions can be achieved under different designs:a. in different parts of a cell,
b. in time intervals of the same system
c. in separate systems operated serially (hybrid design)
Gasith Ecology Consulting 28
HSSF - supports anaerobic conditions
VSSF - supports aerobic conditions
Gasith Ecology Consulting 29
HSSF - supports anaerobic conditions
VSSF - supports aerobic conditions
Hybrid system operation
Gasith Ecology Consulting 30
VSSF HSSF
FF
3 stage hybrid operation
Photo: Internet
Photo: Internet
Photo: Internet
Gasith Ecology Consulting 32
Green et al., 2006Passively Aerated Vertical Bed
Improvement of CW operation by passive aeration
Gasith Ecology Consulting 33
Improvement of CW technology reduced the area required per unit treatment
Activated sludge
Oxidation ponds
Free flow CW
Subsurface Flow
horizonthal
X 4.4X 16.7X 50X 801
Subsurface Flow vertical
Gasith Ecology Consulting 35
In Israel the technology exists for quite a while but is not yet widely distributed
Gasith Ecology Consulting 38
CW as a go‐between polishing system for stream reahbilitation
Upgrading low quality effluents
Effluent quality control assurance
WWTP StreamCW
input
output
desired
pollu
tant
pollu
tant
Gasith Ecology Consulting 40
Summary and Conclusions• CWs are low-tech, environmental friendly, low cost wastewater treatment/polishing systems;
• They can be useful for treating small communities and small agricultural andindustrial operations;
• Efficiency of treatment can be regulated by modifying structure and flow pattern;
• CWs can function as “dialysis” units for rehabilitation of streams;
• Israel’s first large-scale CW system is aimed to improve Yarqon’s stream water quality
Gasith Ecology Consulting 41
Treatment of Secondary Effluent
by Constructed Wetlands
Dana Milstein
EF-CW Workshop, SWITCH Project, WP 3.3
42
Wastewater (Israel 2008: 460MCM)
Sewage System (>90%)
Effluent
Wastewater Treatment Plant (ca. 70% secondary or less)
Micro-pollutantsConventional pollutants
SoilSurface water
Sediment Soil interstitial water
Groundwater
(76%) Irrigation
(24%)streams
43
Shafdan Constructed Wetland
Shafdan secondary effluent
1 2 3 4 5 6 7Treatment efficiency
1. System maturation
(age)
2. Vegetation composition
3. Flow pattern
4. Contaminants load
50
Cumulative removal (%)Inflow
Stage1+2+3
Stage1+2
Stage1
Removal mechanisms
(mg/l)Parameter
556666Bioticdegradation
6.1±4.0BOD
557775Filtration andsedimentation
5.2±3.1TSS
899795Nitrification 2.2±1.1NH4-N
-5-110-235Denitrificationuptake
0.6±0.2NO3-N
52257Nitrification+Denitrification
4.8±1.1TN
-8-20-22-1.2±0.4PO4-P
Removal Efficiency (3rd year)
55
Shafdan constructed wetland
(mg/l)
Inbar criteria
(mg/l)
Effluent following
SSF+SSF+SF
Effluent
following
SSF+SSF
InflowDischarge
into
streams
IrrigationVariable
0.19±0.23
(0.98)
0.06±0.08
(0.41)
2.2±1.1
(4.0)
1.520NH4
2.7±1.0
(5.6)
2.1±1.0
(4.3)
6.1±4.0
(18.6)
1010BOD
2.3±1.9
(7.0)
1.2±1.2
(9.2)
5.2±3.1
(16.8)
1010TSS
0.7±0.6
(2.0)
2.1±1.2
(4.9)
0.6±0.2
(1.1)
--NO3
2.3±1.0
(4.6)
3.6±1.6
(6.2)
4.8±1.1
(6.3)
1025TN
1.3±1.3
(1.9)
1.5±0.5
(2.8)
1.2±0.4
(2.1)
15TP
Effluent Reuse
56
P-Problem?
The ProblemEutrofication in surface water
Solution
P removal in WWTPHybrid technologies
57
N=22 Estradiol (E2) Estrone (E1)
Average (ng/l) 10.6 24.2
SD (ng/l) 8.4 14.5
SE (%) 79 60
Median (ng/l) 7.7 22.9
Min (ng/l) 3.7 4.9
Max (ng/l) 38.7 64.0
Estrogen in the Shafdan Secondary Effluents
Estriol (E3) < 5 ng/l
Ethynylestradiol (EE2) < 2ng/l
Mestranol (MeEE2) < 2ng/l
59
20.5
2.2 2.0 2.0
7.7
2.53.7 3.0
0
5
10
15
20
25
30
inflow poly no veg mono
Estr
og
en
s (
ng
/l)
E1 E2
pondst1Following treatment in the E2 removal>70%E1 removal>90%a
a
b b bb b b
Estrogen Removal in CWEffect of vegetation composition
61
0
20
40
60
80
100
120
Re
mo
val (
%)
VSSF with plants VSSF no plants
Pharmaceuticals Personal Care Produces
Matamoros et al., 2007
• Treatment of municipal wastewater•Hydraulic residence Time: 3-6 Hr
PPCP Removal in CWEffect of vegetation composition
62
Conclusions
•CW represents an aesthetic environmental friendly technology
•CW can upgrade secondary effluent to “Inbar Criteria” (ammonia)
•CW are suitable as “quality control” systems for stream
rehabilitation (e.g.: BOD and TSS)
•CW have limited ability to remove phosphorus
•CW (VSSF) can remove organic micro-pollutants from municipal
secondary effluent
•CW design should be site-specific (omposition and concentration of
contaminants) 63
Acknowledgments
Shafdan WWTPMinistry for environmental quality, ItalyPorter school of environmental studies, Tel-Aviv UniversityMinistry for science, cloture and sport, Israel (Eshcol scholarship) Rigger Foundation, USA-Fellowship ProgramOfra Aqua Plants (system construction)Moran Consultant & Development (system upgrade)
64